A typical gas turbine engine includes one or more turbine rotors configured to extract energy from a flow of combustion gases directed through the engine. Each rotor includes an annular array of blades coupled to a rotor disk. The radially outermost boundary of the flowpath through the rotor is defined primarily by a turbine shroud, which is a stationary structure that circumscribes the tips of the blades. As is generally understood, the various rotor components operate in an extremely high temperature environment and it is often required that the components be cooled by an air flow to ensure adequate service life. Typically, the air used for cooling is extracted (or bled) from the compressor, which negatively impacts the specific fuel consumption (“SFC”) of the gas turbine engine.
In the past, it has been proposed to replace metallic shroud structures with materials having improved high-temperature capabilities, such as ceramic matrix composite (CMC) materials. These materials have unique mechanical properties that must be considered during the design and application of a turbine component, such as a shroud segment. For example, when compared to metallic materials, CMC materials have relatively low tensile ductility or low strain to failure, and a low coefficient of thermal expansion (“CTE”). One type of segmented CMC shroud incorporates a rectangular “box” design.
Conventionally, shroud segments have been coupled to an outer turbine structure, such as a shroud hanger, using a very tight friction-based fit. For example, it is known to radially retain shroud segments via a standard C-clip that utilizes an interference fit to couple the shroud segment to its corresponding shroud hanger. Unfortunately, interference-type fits are typically not appropriate for CMC-based and other non-metallic-based shroud segments given that the shroud segments are extremely susceptible to edge damage and other types of damage when the component(s) providing the interference fit is installed onto and/or around the shroud segment.
Accordingly, an improved shroud retention system for radially retaining a shroud segment relative to a shroud hanger that does not rely on an interference fit(s) would be welcomed in the technology.